Are fingernails and tooth bones

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The hypodontic nail dysplasia syndrome belongs to the group of ectodermal dysplasias. The prevalence is estimated at 1-2: 10,000. The primary teeth are usually inconspicuous, the permanent teeth often do not erupt. Often the incisors and second molars are missing in the lower jaw and the canines in the upper jaw, and the crowns are small and conical. The lips can be everted. The nails are usually small, thin and brittle and have longitudinal grooves, dimples or a trough-shaped indentation (koilonychia). Congenital lack of the nail plate has also been reported. Usually the toenails are more severely affected than the fingernails. Sweat glands, heat tolerance, and hair are normal. In some cases, however, fine hair has also been reported. The syndrome is inherited as an autosomal dominant trait. The cause is mutations in the MSX1Gene (chromosomal region 4p16.1). The diagnosis is usually made in middle age when the persistence of the deciduous teeth is noticeable. However, in cases with only minor changes in the nail, diagnosis of the syndrome can be difficult. Other forms of ectodermal dysplasia can be excluded from the differential diagnosis, especially hypohidrotic ectodermal dysplasia (see there). There is no specific therapy, care must be taken with oral hygiene and dental care. The prognosis is good. With age, the nails show fewer changes and then often appear quite normal in adulthood.

Reviewer: Pr Alain VERLOES - Last update: March 2007

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